The invention relates to a tape reel on which is wound magnetic tape of the kind which is typically used in the computer industry. With the increasing speed of present day computers, the need for increasing the amount of information stored on a computer tape reel has increased proportionately. To obtain more information on a computer reel, thinner magnetic tapes which are wound more tightly on the reel have been proposed and utilized. To increase the amount of tape wound on the tape reel, the tape has in essence been compressed more tightly on the tape reel. This has resulted in increased compressive loading on the central hub of the reel which includes the tape winding ring about which the tape is wound.
Prior magnetic tape reels which were used to wind magnetic tapes at normal tensions have been found not entirely suitable for the increased tape densities and tensions. Two of the main problems are structural failure of the central winding hub and flaring in or out of the outer edges of the reel flanges which are attached to the central hub. In prior tape reels, the larger compressive forces encountered by increased tape density and winding tensions have caused the edges of the reel flanges at their outer diameters to deform slightly in or out which causes uneven winding of the tape on the reel. Even slight deformation of this nature can cause the tape to wind in a conical manner bearing more or less against one of the flanges instead of being squarely wound on the hub. This conical winding tends to impart stresses to the flange which can cause it to fracture from the hub and possibly result in destruction of the tape being wound on the tape reel.
Numerous proposals have been made in order to strengthen the tape reel, and in particular the central hub, for accommodating the larger tape densities and winding tensions. For example, in U.S. Pat. No. 4,044,965, a box-like structure is provided by four annular continuous cylindrical welding surfaces between the reel flanges and the central hub. The box-like structure is said to effectively accommodate the increased compressive forces by transmitting the force from the tape winding ring, through the sides of the box which are formed through ribs on the flanges, to the spindle mounting ring of the tape reel. It is said that this box structure is sufficiently rigid and undeformable to avoid the hub tightening on its driving spindle, the flanges buckling, and the ring losing its cylindricity, while the tape is being wound. While the four annular welding surfaces are continuous about the mating surfaces of the reel flanges and the central hub, U.S. Pat. No. 4,327,879, has sought to accomplish the box-like strcuture by utilizing non-continuous welding surfaces. In U.S. Pat. No. 4,327,879, it was thought that the reel of U.S. Pat. No. 4,044,965, suffered the primary disadvantages of not being able to maintain consistent welding throughout the circumference of the reel. This is due to part-to-part irregularities and flange-to-hub misalignments which would prevent full circumferential contact between the annular collars of the central hub and the welding surfaces of the side reel flanges. The continuous annular contact is thought to be unattainable due to these part inconsistencies and processing misalignments which could result in inconsistent weld areas and resulting part rejection. In U.S. Pat. No. 4,327,879, the thought of using spokes extending radially outward from the tape winding ring and the tape winding hub was proposed wherein the spokes were spaced circumferentially around the central hub. Corresponding mating surfaces of the tape reel flanges, also provided in a noncontinuous manner around the circumference of the parts, were then made to align with the spokes on the central hub. Box-like structures where provided at the sections where the central hub and the side flanges were made to contact one another. The teaching of U.S. Pat. No. 4,327,879 then is that the continuous welding surfaces which provide a box-like structure in U.S. Pat. No. 4,044,965 were not necessary and that only point contact welding surfaces are needed at circumferential intervals around the reel.
Other proposals are found in U.S. Pat. Nos. 4,083,509 and 4,088,278 which are very similar. The general concept in these two patents is that the reel flanges are not connected to the spindle mounting ring of the central hub, but rather are attached and welded between the tape winding ring and an intermediate ring. In one sense, these two patents merely shorten the box-like structure which was sought to be obtained in the aforesaid two patents. This is accomplished by moving the lower attachment points of the flanges from the sprindle mounting ring radially outwardly to an intermediate ring. In U.S. Pat. No. 4,083,509 the side flanges are attached underneath or to the radially inward side of the intermediate ring. In U.S. Pat. No. 4,088,278 the side flanges are attached to the radially outward side of the intermediate ring.
Generally speaking, the gist of the four patents described above, has been to provide a box-like or other structure for reinforcing the tape reel against compressive loading. The structures provided have attempted to take the compressive forces from the tape winding ring, transmit them through a rib or other structure of the side flanges, and then transmit them through the side flanges to the spindle mounting ring or intermediate ring of the central part. The box-like structure offers a high resistence to compression produced by the tape being wound on the reel. The problems encountered by these approaches are that when the reel flanges are used in such a manner to provide components of the box-like or other structure which resists compression, it is inevitable that some influence is made on the reel flanges or some slight deformation regardless of the strength of the box-like structure.
As recognized in U.S. Pat. No. 4,083,509 other problems are caused by the asymmetrical nature of the forces produced by the asymmetrical designs of the central hubs of some of the prior patents. The teachings of U.S. Pat. No. 4,083,509 is to design the central hub so that its parts are offset with respect to each other so that the forces which resists deformation are generally equally distributed on opposite sides of the plane normal to the reel axis passing through the axial center of the reel. Symmetrical force distribution then is taught by having an asymmetrical hub design which compensates for the different structures and force loadings of the front and back reel flanges. In so doing, however, the assembly process of the reel is made complicated due to the asymmetrical hub design and fitting of the parts together to such an assymetical configuration.
Accordingly, an important object of the present invention is to provide a magnetic reel which accommodates the increased tape density and tape winding tensions utilized in present day high-speed computers without any appreciable deformation of the reel parts.
Still another important part of the present invention is to provide a magnetic tape reel wherein the forces of compressive loading of the tape being wound on the reel are transmitted mainly through the central hub part itself and not the reel flanges.
Still another important object of the present invention is to provide a tape reel having a symmetrical central hub making it easy to manufacture and assemble with the side flanges.
Still another important object of the present invention is to provide a magnetic tape reel having a central hub which is symmetrical about a plane normal the reel axis passing through the axial center of the reel such that the forces of compressive loading placed on the central hub are transmitted symmetrically through the central hub on either side of the normal plane.
Still another important object of the present invention is to provide a tape reel for accommodating increased tape densities and winding tensions which includes a central hub having a number of circumferentially spaced transverse "Y" shaped web sections which resist the forces produced by compressive loading while the tape is being wound on the reel.